There's a documentary called "Fat Head", which is a response to "Super Size Me" and it also talks about losing weight whilst eating at McDonalds. It's been a while since I saw it, so I don't even want to paraphrase what it's about, but it has interviews from Mary Enig, Sally Fallon and Michael Eades, so you can guess what the general gist is.
As for the experiment, of course he's going to lose weight. If he weighed 280lbs in the beginning and exercised 45 minutes every day, then his expenditure must've been around 3650kcal per day. That would mean a 1650kcal daily deficit on a 2000kcal diet. So...duh :-)
EDIT: I calculated his BMR by approximating his height and age and used the 1.55 multiplier, which is moderate exercise 3-5 times per week, since he was only walking every day. That said, he looked pretty out of shape even when just walking, so his expenditure might've been even higher.
Last edited by SparklyBunny; 01-08-2014 at 12:28 PM.